Thread: Variations in 4BD1 motors

Originally Posted by Dougal

Maybe there are three piston types.

Here I have two. The aftermarket turbo pistons from my last 4BD1T rebuild, these are identical to the factory pistons and have the steel inserts (alfin?).
The other piston is completely aluminium, it was from a a 6BD1 rebuild kit.

These two pistons look quite different, but are exactly the same height from pin to crown. The ring lands are just cut higher on the turbo piston and one land is steel.

There are also taller pistons available. I know this because I accidentally ordered a set once. For what engine I'm not sure, but it was about 4mm taller than the correct set but the same 102mm bore, same gudgeon pin etc.

Alfin inserts are always an "automotive spec" which includes trucks. Non Alfin are most cases an industrial spec where stationary engines run at set revs with little no variation.
The exception is "squeeze cast" where there is no Alfin insert, however these are comparable to a forged piston and are used in automotive spec.

Originally Posted by Dougal

I have a genuine Isuzu piston here which I suspect is for an early 4BD1 or 6BD1. It is taller than my turbo pistons and doesn't have the steel inserts.

If anyone wants it, let me know. It's brand new and I have enough paper weights.

If you give me the numbers either on the piston crown or on the inside of the piston boss, I can tell you exactly what it suits.

Originally Posted by LOVEMYRANGIE

If you give me the numbers either on the piston crown or on the inside of the piston boss, I can tell you exactly what it suits.

0682 stamped into the crown.

Originally Posted by Dougal

0682 stamped into the crown.

Hmm - the 2nd OE number here ends in 0682.


Lovemyrangie, if these are the numbers, would you be able to tell us what application each piston type was used for?

and when did early/late 4BD1 changeover? My manuals seems to say 86/87 in NPRs.

Cheers,

Ben.

Originally Posted by isuzurover

Hmm - the 2nd OE number here ends in 0682.

Measurements seem to match too.

I still have the original Isuzu pistons from my 4BD1T, but the top surface has had a hard life.
They're the short alfin pistons, there's a number on the box in Isuzu's part number format.

8-94321-734-0
Part number for the box of four with gudgeon pins and rings (crap rings, throw them away) etc.
PKIS410206DA

It matches this sheet.
http://www.partstw.com/images/isuzu/isuzu_4bd1t-206.gif

Originally Posted by isuzurover

Hmm - the 2nd OE number here ends in 0682.


Lovemyrangie, if these are the numbers, would you be able to tell us what application each piston type was used for?

and when did early/late 4BD1 changeover? My manuals seems to say 86/87 in NPRs.

Cheers,

Ben.

Ben ring me on my work number 0437 377 619 and when I am in the office I will run thru the numbers with you.
Using Chinese copy product references are not always the best reference source as they will not have all the details, just copied part number products.
Regards
Andrew.

I emailed Isuzurover some info on the Izumi numbers I have at work for LR, but forgot to email it to my home address too

I will put up the post tomorrow when I get in to the office as I am finally taking the S2A trailer I've been building over the pits tomorrow morning for its first inspection!! Wooohooo!!

This is the info that Andrew (Lovemyrangie) emailed me (Thanks Andrew!):

4BD1 Landrover spec
Our part # P2081
5121112421 - PISTON & PIN (Squish Lip) 98.1mm Non Alfin
(Number on crown = 2421, 6360)
Suits 4BD1 non turbo Landrover spec only
Combustion bowl Ø = 50.95mm (Side to side) Square combustion bowl
Overall length of 98.1mm
Has 2 x valve relief
Strutted type piston
Non Oil cooled crown

4BD1T Landrover spec
Our part # P2030
(8-94175027-2,
8-94321734-0,
8-97176836-0,
5121117340) - PISTON & PIN (Squish Lip) 98.1mm Alfin
(Number on crown = 0272, 7340 , 8360)
Suits also 4BD1T NPR/NPS59 2/87>
4BD1T Landrover spec all, for non turbo spec use P2081
Can use in 4BD1 non turbo NPR59 2/87> as well, original piston in this one has no valve relief
Combustion bowl Ø = 51.05mm (Side to side) Square combustion bowl
Overall length of 98.1mm
Have 2 x valve relief
Strutted type piston
Non oil cooled crown

These are for LR issue engines. Any other configuration would be a conversion.
All turbo engines are late engines, ie have 98mm height.

Regards

Andrew.

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